The Food and Drug Administration recently approved a new test to rapidly diagnose dengue infection in humans. The test, developed by the Centers for Disease Control and Prevention, differs from previous dengue tests because, instead of detecting antibodies produced in response to the dengue virus, it can detect the virus itself.
The first FDA approved test for dengue, the DENV Detect IgM Capture ELISA, approved last year in April 2011, was only able to detect immunoglobulin M (igM), a particular antibody (which is a protein developed by the immune system when harmful foreign microbes are detected) to the dengue virus in infected patients. While most patients develop detectable antibodies within four days after symptoms of dengue infection begin, these antibodies are not always present until seven days after infection. So, the virus may be present in the system for a long time before antibodies are developed and detected. This makes it difficult for doctors to provide a definite dengue diagnosis when patients seek early medical attention based on symptoms. In dengue cases, a missed diagnosis can often lead to the delay of appropriate treatment and increase the risk for mortality. That the new CDC test can detect the virus, rather than just the antibodies, is a significant improvement.
The new test, called the CDC DENV-1-4 Real Time RT PCR Assay, is able to detect all four types of dengue virus within the first seven days after symptoms appear. The timeliness of the test is critical since most people are likely to seek medical care within those first seven days of infection (and while experiencing symptoms) and the virus is most likely to be present in the blood during that timeframe. Another advantage the new test offers is easy adoption and implementation: the test can be performed with equipment and supplies commonly available in public health laboratories. In sum, the new test makes early diagnosis, early treatment, and better patient monitoring more likely. While there is no vaccine or specific treatment for dengue infection, supportive therapies and careful monitoring for complications can be critical to recovery.
Dengue is a mosquito-borne viral infection endemic in tropical regions, affecting up to 100 million people worldwide annually. The infection causes flu-like illnesses in infected patients, and is characterized by high fever, headaches, severe pain behind the eyes, body aches, rash, bruising, and mild bleeding in the nose or gums. Severe cases of dengue can lead to hemorrhagic fever, shock, organ failure, and is often fatal if left untreated.